Electrical system



Jupe 21, i949." P, w. sTUTsMAN l ELECTRICAL SYSTEM 2 shets-sheet 1 FiledApril 14, 1944 P. w. lsTUTsMAN ELECTRICAL SYS TEM June 21, 1949.

Filed April 141944 2 Sheets-Sheet 2 VVVVVVVV Patented June 2.1, 1949ELECTRICAL SYSTEM Paul W. Stutsman, Needham, Mass., assignor, by

mesne assignments, to Raytheon Manufacturing Company, Newton, Mass., acorporation of Delaware Application Apri1 14, 1944, serial No. 531,067

7 Claims.

This invention relates to electrical systems and more particularly toelectrical signal systems for visible signalling.

Electrical signalling systems are known in which a relay and signal lampare used to produce a visible signal. These systems, however, areobjectionable, particularly in portable systems, on account of theweight of the relays.

One of the objects of the present invention is to provide an electricalsignalling system in which this difficulty is overcome by substituting anovel tube that makes it possible to do away with the relay.

Electrical signalling systems heretofore used are also open to theobjection, when it is desired to use a very small signal voltage, thatthey require the application of a relatively higher voltage in order tolire the tube. The present invention overcomes this objection byproviding two auxiliary electrodes in addition to the anode and cathode,and so arranged that when a signal in put voltage is applied betweensaid two auxiliary electrodes and the anode and cathode respectively,the signal input voltage will be added to the cathode-anode voltage toraise the voltage across a gap within the tube to the breakdown point,the magnitude of the signal input voltage required to be added beingrelatively small, so that tubes embodying the present invention may bemade to re on a very low signal input voltage.

In such electrical signalling systems, transient voltage differences mayoccur between different circuits which may not only be disturbing butmay even re the tube.

Another object of the present invention, therefore, is to eliminate theeffect of such transient voltage differences.

When devices of the above type are used in telephone systems comprisinga plurality of signal circuits, there is a tendency to produce what isknown as crosstalk, that is to say, conversation upon one linereproduced upon another. A further obj ect of the present invention isto eliminate such crosstalk or to attenuate it sufficiently to render itunobjectionable.

A further object of the present invention is to provide an improvedgaseous conduction tube.

These and such other aims and objects of the present invention as mayhereinafter appear will be readily understood from the followingdescription, taken in connection with the accompanying drawing, ofembodiments of the invention herein presented for illustrative purposes.

In the drawing: Fig. 1 is a vertical cross-section on line I-I of Fig. 2of a tube embodying one illustrative embodiment of certain features ofthe invention;

Fig. 2 is a horizontal cross-section on line 2-2 of Fig. 1 but showingthe tube elements inplan;

Fig. 3 shows an electrical signalling system embodying one illustrativeembodiment of the invention;

Fig. 4 shows an electrical signalling system embodying anotherillustrative embodiment of the invention; and

Fig. 5 illustrates an electrical signalling system embodying a furtherillustrative embodiment of the invention.

Referring to Figs. 1 and 2, in the illustrative embodiment of theinvention therein shown, the signal lamp comprises a glass envelope 2containing a suitable ionizable gaseous medium and an electrode assemblycomprising a cathode 4, an anode E, and two grids or auxiliaryelectrodes 8 and lo. Said cathode may be relatively large and in thisillustrative embodiment of the invention is shaped like an inverted bowlprovided with a relatively large, central circular aperture I2 throughwhich said anode 6 and the two auxiliary electrodes 8 and I0 extendupwardly. The lower ends of said anode and said two auxiliary electrodesare sealed in a press I4 formed upon the upper edge of the reentrantstem I6 of said envelope, the lower edge of said envelope 2 beinghermetically sealed'to the flare I8 of said stem IVE. Above saidcathode, said auxiliary electrode 8 is shown as bent horizontally awayfrom the anode, then downwardly, and then circularly in a planesubstantially parallel and in proximity to the upper surface of saidcathode, this portion of said auxiliary electrode thus forming almost a.complete circle and presenting an extended active area to the upperelectron-emissive surface of said cathode. The auxiliary electrode Illextends substantially parallel to the anode 6, its upper end being bentat right angles across the latters upper end. Means may be provided toprevent premature ignition, such as a shield 20 surrounding the anode 6,and herein conveniently consisting of a glass cylinder integral withsaid stem I6. The cathode is supported by a post 22, the lower end ofwhich is sealed in said press I4. A conductor 26 connects the cathodewith a lead-in conductor 28, and the lower ends of said anode and ofsaid two auxiliary electrodes 8 and lil are joined to lead-in conductors30, 32 and 34, respectively.

The signal lamp as above described, including the electrode assembly andother parts therein contained, may and preferably will be the same 3 forall embodiments of the present invention herein disclosed. In thedescription of Figs. 3, 4 and 5 therefore, such parts of the tube as maybe referred to will be designated by the same reference numerals as inFigs. 1 and 2.

Referring to Fig. 3, auxiliary electrode 8 is connected bya conductor 32to one terminal 36 of the signal input circuit, and auxiliary electrodeI is connected to the other terminal 38 of said signal input circuit byconductor 34 through a resistance 56. It may be advantageous to use a.voltage storage device, such as condenser 44, in this circuit as will behereinafter more fully explained. The conductor 26, joined tothe cathode4, is connected by conductor 2B to one pole 48 of a battery or othersuitable source 50 of D. C. voltage which may be adjustable 'and anode 6lisvcon-v nected to the other pole 52 of said source by conductor 30.will preferably, be included in said anode-cathode circuit.

In this embodiment of the invention when volt'- ages of from 135 to.:180-volts are available; neon gas may be used at'a pressure of 40 mm. ofmercury.

The-signal discharge'may'be initiated in either one of two ways or both.It may be initiated directly between the twoiauxiliary electrodes andIllJ to produce sufcient'ionization for the discharge to startbetweenthe cathode 4 and the anode 6. It isconceivable', however, thatfor some reasonthe initiationof the discharge might not take placebetween said two auxiliary electrodes. Such a condition might 'existifthe spacing of said two auxiliary electrodes were too great fortheavailablesignal voltage alone to break down, or the signal voltage.might be too low to effect abreakdown evenif the spacing of said twoauxiliary electrodes were at the minimum breakdown distance. Insuch caseit` has been found that the'discharge may be initiated between theauxiliary electrode 8 and kthe cathode 4, and between the auxiliaryelectrode I0 and the anode 6. It is believed that this may be due to thefact that the signalvoltage may build up a potential on saidiauxiliaryelectrode.` 8, which is lpositive with respect to said'auxiliaryelectrode I8, and the anode-cathode voltage makes the anode 6 positivewith respect tothe cathode4 4. Under these conditions, thesignalivoltage willadd to the anode-cathode voltage and. thus the totalvoltage impressed across: the gaps between `the auxiliary electrode 8andthecathode 4'and between the auxiliary electrode I Uand'theanode Bwill be thesumpf said signal and anode-cathode voltages. The'voltagesacross these gaps may thus be raised to the breakdown point. If .thistheory is correct the magnitude of the signal input'voltage required` toproduce breakdown becomes a function of the `anode-cathode voltage,increasing and decreasingginversely to the increase or decrease of theanode-cathode voltage.

To illustrate, let us consider Fig. 3. As pointed out above, when theauxiliary electrode 8 is positive with respect to theauxiliary'electrode I0, then voltage from the signal voltage will beadded to the anode-cathodevoltage 50, across the gaps 4 8 and `I 8 6.

Let us suppose that the anode-cathode circuit voltage Ea is 180 voltsD.,C., that the voltage required for breakdown between cathodev 4 andthe auxiliaryelectrode `8.is 110 volts, and that the samevoltage willbe` required. for breakdown be- A current-limiting resistance 58 tweenanode y6 and.'auxiliary electrode |0, The

necessary starting potential to break down both 4 gaps 4--8 and I--would therefore be 220 volts, which is made up of D. C. voltage,supplied by the anode-cathode circuit 50, and A. C. voltage supplied bythe signal input circuit 5I. If we designate by Es the R. M. S. A. C.voltage of the signal input circuit 5 l, then ES=EO Sin wt where E0designates the peak signal input circuit voltage. The tube willtherefore fire when (l) Ea-i-Eo sin wt=220 volts Thus i (2) 220volts-Ea=Eo sin wt But we know that (3) Ea=180 volts therefore from (2)(4) 220 volts-180 volts=40 volts and (5) Eo=40 volts when Sin wt=1 Thesignal input' circuitvoltagerequired to be added' to thel'peak'voltageof the anode-cathode circuit for starting the tube would be 40 voltspeak, or; reduced to R. M. S. A. C., it would be equal to The signalinput circuit voltagerequired .to start the tube is therefore a-functlonof the applied anode-cathode'circuit voltage. Once initiated between thecathode and auxiliary electrode 8, .the discharge will pass on throughthezsignal input circuit to auxiliary/'electrode l0.and.from the latterto the anode. Thereupon thefdischarge is nally initiated between .saidanode and cathode.

It has beenstated abovelth'at the use ofa condenser in thesignal inputcircuit might be advantageous. Ithasbeen found infact that under certainvconditionswthe Luse 'of Ta condenser, shown at44'in Fig. 3,' reducesthestarting voltage. Thus, with a condenser having a capacitance of .005microfarad, theslgnal starting voltage-'Was' reducedfrom rrvoltsR. M. S.to50 volts'R. M. S. and the :peak from 91 vvoltsto 70 volts.

When a plurality of devices. as. illustrated in Fig. Bare utilized 1inVa; single telephone system where the voice signals also appeal-:acrossthe lines 32fand 34, there will be substantially no tendency toproduce-crosstalk'.A since there :is vsubstantially infinite impedancebetween thesignalinput circuit and the anode-cathodescircuit vwhen thetube is not conductingI as is theoase during the `period when speech isbeing=transm.itted,` and thus no crosstalkI caribe transmitted,Referring to.-Fig. 3 -it will beeseen that-as previouslystated, in .theillustrative embodiment f of. the invention therein shown,` theauxiliary. electrode 8 is directlyfconnected to one terminaly3irof-fthesignal input circuit byfconductor. 32 andthatauxiliaryelectrode l0 is directlyconnected to theother terminal `38 ofy saidcircuit bysconductor 34. The signal input circuit is therefore.disconnected externally from the anode-cathode circuit,so that asabovestated, when the tubeis-not conducting,- thereis -substantiallyinniteimpedance .between'the signal input circuit and theanode-cathodecircuit and crosstalk is excluded.

In the embodiment;v `of the :inventionillustrated in Fig. 3, theauxiliary electrodes 8 and l0 float ammessa This is duey at least inpart to the favorable relative positions of said two auxiliaryelectrodes 8 and l to the other elements of the tube and the associatedcircuit. While the potential required for ignition has been reduced,premature ignition between the anode and the cathode, before a workingvoltage has been attained, is prevented by suitable means, such as ashield 20 (see Fig, l), that encloses the anode throughout that partwhere such premature ignition might occur. The signal input voltage maybe made as low as may be desirable.

I Firing of the tube except when the desired and necessary signal inputvoltage is applied, and which was heretofore caused by transientdisturbing voltage differences that may occur between circuits, has beeneliminated and crosstalk in those systems wherein it is likely to occurhas also been substantially eliminated or so attenuated that it isunobjectionable.

Systems embodying the present invention are also considerably lighter inweight where the lamps take the place of lamps and relays. Otheradvantages will suggest themselves to those skilled in the art.

I am aware that the present invention can be embodied in other specificforms without departing from the spirit or essential attributes thereof,and I therefore desire the present description to be considered in allrespects as illustrative and not restrictive, reference being had to theappended claims rather than to the aforesaid description to indicate thescope of the invention.

What is claimed is:

1. In an electrical system, a gaseous conduction tube comprising anhermetically sealed envelope containing an electrode assemblycornprising an electron-emissive cathode, an anode and two auxiliaryelectrodes; an anode-cathode circuit comprising said anode and saidcathode; a signal input circuit comprising said two auxiliaryelectrodes; and means comprising a bypass condenser, connected betweensaid two circuits, for by-passing transient voltage differences thatmight occur between said two circuits thereby preventing said transientvoltage differences from ring the tube.

2. In an electrical system, a gaseous conduction tube comprising anhermetically sealed envelope containing an electrode assembly comprisingan electron-emissive cathode, an anode and two auxiliary electrodes; ananode-cathode circuit comprising said anode and said cathode; a signalinput circuit comprising said two auxiliary electrodes; resistance meansconnected between said two circuits; and condenser means shunted aroundsaid resistance means.

3. In an electrical signal system, a gaseous conduction tube comprisingan hermetically sealed envelope containing an electrode assemblycomprising a glow discharge cathode, an anode and two auxiliaryelectrodes; an anode-cathode circuit comprising said anode and saidcathode; a signal input circuit comprising said two auxiliaryelectrodes; and means comprising a by-pass condenser, connected betweensaid two circuits, for ley-passing transient voltage diierences thatmight occur between said two circuits thereby preventing said transientvoltage diierences from firing the tube.

4. In an electrical signal system, a gaseous conduction tube comprisingan hermetically sealed envelope containing an electrode assemblycomprising a glow discharge cathode, an anode and rtwo auxiliaryelectrodes; ananode-cathode circuit comprising said anode and saidcathode; a signal input circuit comprising said two auxiliaryelectrodes; resistance means connected between said two circuits; andcondenser means shunted around said resistance means.

5. In an electrical signal system, a gaseous conduction tube comprisingan hermetically sealed envelope containing an electrode assemblycomprising a glow discharge cathode, an anode and two auxiliaryelectrodes; an anode-cathode circuit comprising said anode and saidcathode; a signal input circuit containing said two auxiliary electrodesand current-limiting resistance means; and condenser means connectedbetween said two circuits.

6. A glow discharge lamp comprising a sealed envelope containing alight-producing gas at substantial pressure, said envelope having aninsulating stem through which a plurality of conducting leads aresealed, an insulating sleeve projecting into said envelope from saidstem and surrounding one of said leads, said sleeve being open at itsinner end to permit the inner end of the lead which it surrounds to actas an anode, a cup-shaped cathode supported by another of said leads,said cathode having its convex surface facing away from said stem andhaving a central opening through which said sleeve projects, anauxiliary ring-shaped electrode supported by another of said leads andlying closely adjacent the convex surface of said cathode, and a secondauxiliary electrode connected to another of said leads and overlying theopen inner end of said sleeve in close juxtaposition to the anode.

7. A glow discharge lamp comprising a sealed envelope containing alight-producing gas at substantial pressure, said envelope having anin'- sulating stem through which a plurality of conducting leads aresealed, an insulating sleeve projecting into said envelope from saidstem and surrounding one of said leads, said sleeve being open at itsinner end to permit the inner end of the lead which is surrounds to actas an anode, a cup-shaped cathode supported by another of said leads,said cathode having its convex surface facing away from said stem andhaving a central opening through which said sleeve projects, anauxiliary ring-shaped electrode lsupported by another of said leads andlying closely adjacent the convex surface of said cathode, a secondauxiliary electrode connected to another of said leads and overlying theopen inner end of said sleeve in close juxtaposition to the anode, andan opaque shield surrounding said envelope, said shield being providedwith a window at one end whereby the light generated at the convexsurface of said cathode may be observed through said window.

PAUL W. STUTSMAN.,

REFERENCES CITED The following references are of record in the rile ofthis patent:

UNITED STATES PATENTS Number Name Date 1,144,596 Hewitt June 29, 19151,506,468 White Aug. 26, 1924 1,550,877 Chaffee Aug. 25, 1925) 1,838,871Schmierer Dec. 29, 1931 1,893,638 Schmierer Jan. 10, 1933 1,947,774Heany Feb. 20, 1934 2,113,464 Hazeltine Apr. 5, 1938 "5 withrespect tothe anodeandcathode. This has a tendency to renderthe tube somewhatunstable. To remedy this and to stabilize the tube it is preferabletoprovide stabilizing means, such as, for example, a grounded shieldfSD ofmetal or other suitable electrically conductive material. A(See Fig, 3.)If desired :said shield may completelyenclose the tube except at fthetop and bottomthereof so as to conne the light to what `isemittedthrough the top of said'shield. If desired the light from the tube maybe further localized by insertionof a lens 93 in the top of the cylinder90.

Ystabilizing circuit arrangements may also be .utilized such as showninthe illustrative embodiment of Fig. 4. In this embodiment theauxiliary electrode 8 is connected by conductors 32 and 68 to oneterminalv62 of the vsignal input cir- .cuit and the auxiliary electrodeI is connected by conductors 34 and 64' to the other terminal 66 of saidcircuit, a current-limiting resistance 68 4being preferably inserted insaid circuit. The anode 6 is connected to the'positive pole of a sourceof D. C. voltage, battery 80, for example, for the anode-cathode circuitbyconductors 30 and 82 through a resistance 84 for limiting the anode-.cathode current to working value, and the cathode 14' is connected tothe negative pole of said source of D. C. voltage by conductors 28, v28,8l and 88. The auxiliary electrode 8 is also connected to the negativepole of said source of D, C. voltage 88 by conductors '32, 9|, 81 and 8Bthrough a rela- 'tively high resistance 'I0 and a current-limitingvresistance 68, and the auxiliary electrode is also connected to ksaidnegative pole of said source of D. C. voltage 88 by 'conductors 34, 92,9|, 8'!

-and 88 through a relatively high resistance le.

I have discovered that by using a discriminatory impedance networkconnected between the anode-cathode circuit and the signal input circuitvand comprisingfor example, a by-pass condenser 1.2 shunted around saidresistance 1B, and a sec- .ond by-pass condenser T6 shunted around said.resistance 14, the benetsof circuit stabilization .are secured withoutintroducing diiiiculties, such as undesired firing and crosstalk.

I have found that the transient disturbances .which tend to produceundesired firing are of relatively high frequency asfcompared to thosevoice .frequencies which carry the intelligible portions of the voicesignal and said Voice frequencies are relatively high as compared to thesignal frequencies. Due to said frequency diierences, the impedance ofthe members 12, 'l0 and 16, 'M can be made sufficiently low, relative tothe undesirable transient voltage diiferences that may exist be- .tweensaid anode-cathode circuit and said signal input circuit and which mightotherwise fire the tube, to by-pass said transient voltage, and yetsufficiently high with respect to the signal frequencies so as to permita suiiiciently high signal voltage to be built up across said impedanceto fire the tube. By a suitable adjustment of said impedance, crosstalkdue to intercircuit coupling,

vvented by said condensers ||2 and H4.

rata higher voltage such as 135 to 180 volts. ypointed out above wheresuch a higher voltage Whenz an anode-cathode voltage from to 135 4voltsisavailable, avgaseous medium composed of a mixture of neon and argongases (about 34.4 mm. of neon to 0.6 mm. of argon) may be used in theembodiment of '.Fig. 4. If higher voltages were available and asairesult a neon-rilled tube were to be used in the arrangement of Fig.4, a continuous small discharge may be present be tweenthe anode andauxiliary electrode I8 due 'to the vconnections afforded by theresistances l"Hl and 14. Should'ithis be objectionable the embodiment ofthe inventionillustrated either in Fig. `3 `or inlig. 5 is preferable.

In the illustrative embodiment of the invention shown'inzFig` 5,auxiliary electrode 8 is connected through a currentlimiting resistance|08 to terminal 96 of the signal'input circuit by conductors 32,102 andauxiliaryV electrode I0 is connected through a current-limitingresistance ||0 to terminal 98 of said circuitbyv conductors 34, |86. In

this'embodiment ofzthe invention condensers I2 andi I4, like condensers'l2 and 76 of the-previlously described embodiment of the inventiondisclosed in Fig. 4, can be adjusted to provide an impedance that issufficiently low, relative to the undesirable transient voltagediierences that may exist between the anode-cathode circuit and thesignal input circuit and Which'might otherwise re the tube to by-,passsaid transient voltage differences, and yet to provide a sulciently highimpedance with respect to the signal voltages as .to insure'the buildingup ofy a voltage across said .impedance that will be suiciently high tonre the tube. However, resistances across the condensers ||4 and ||2such as are present in Fig. 4 are omitted. By such judicious adjustmentof said condensers ||2 and ||4 it is possible to cause extraneoustransient voltages to be by-passed and .substantially eliminated, andcrosstalk, due to intercircuit communication when the invention is usedin a system where it tends to occur, to be so greatly attenuated thatitbecomes unobjectionable. These by-pass condensers ||2 and ||4 areconnected to the signal input circuit by t .conductors H6 and ||8,respectively. They are also connected to the anode-cathode circuit,being connected to the negative pole of a source of D. C. voltage, suchas a battery |20 for example, by conductor |23, the cathode 4 beingconnected .to the. negative pole of said battery by conductors 26, 28and |23. The positive pole of said battery is connected to the anode 6by conductor |24 through a current-limiting resistance |26.

As stated above where the anode-cathode voltage exceeds volts, the abovedescribed embodiment is preferable to that disclosed in Fig.

--4, as the continuous small discharge between the anode and auxiliaryelectrode |0 that may be present in said embodiment of Fig. 4 is pre-The system disclosed in Fig. 5 is designed to operate As is used, thetube may contain neon gas at a pres- .sureof approximately 4 cm.mercury.

The invention has been described by Way of yillustration in itsapplication to electrical signalling systems for visible signalling. Itshould be understood, however, that the invention is in nowise limitedto such particular application, certain of its features being equallyapplicable to other electrical systems.

The present invention is a distinct advance in the art. It hasmaterially lowered the potential from the signal .circuit required forignition,

Certicate of Correction Patent No. 2,473,832. June 21, 1949.

PAUL W. STUTSMAN It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionas follows:

Column 8, line 44, claim 7, for the Words which is read 'which it;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case 1n thePatent OIice.

Signed and sealed this 22nd day of November, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommz'asoner of Patents.

